What you need to know about variable scope What is a user-defined variable in JavaScript? All JavaScript programming happens in an environment like a web browser, Node, or Bun.js.

Learn how to make the most of Observable JavaScript and the Observable Plot library, including a step-by-step guide to eight basic data visualization tasks in Plot.

It's been a while since I worked on regexs in JavaScript, but generally the way you do this in most programming languages is to build the regex as a string and then pass it into the regex engine.